Formation, Characterization, and Bonding of cis- and trans-[PtCl2{Te(CH2)6}2], cis-trans-[Pt3Cl6{Te(CH2)6}4], and cis-trans-[Pt4Cl8{Te(CH2)6}4] : Experimental and DFT Study

Abstract

[PtCl2{Te(CH2)6}2] (1) was synthesized from the cyclic telluroether Te(CH2)6 and cis-[PtCl2(NCPh)2] in dichloromethane at room temperature under the exclusion of light. The crystal structure determination showed that in the solid state, 1 crystallizes as yellow plate-like crystals of the cis-isomer 1cis and the orange-red interwoven needles of 1trans. The crystals could be separated under the microscope. NMR experiments showed that upon dissolution of the crystals of 1cis in CDCl3, it isomerizes and forms a dynamic equilibrium with the trans-isomer 1trans that becomes the predominant species. Small amounts of cis-trans-[Pt3Cl6{Te(CH2)6}4] (2) and cis-trans-[Pt4Cl8{Te(CH2)6}4] (3) were also formed and structurally characterized. Both compounds show rare bridging telluroether ligands and two different platinum coordination environments, one exhibiting a cis-Cl/cis-Te(CH2)6 arrangement and the other a trans-Cl/trans-Te(CH2)6 arrangement. Complex 2 has an open structure with two terminal and two bridging telluroether ligands, whereas complex 3 has a cyclic structure with four Te(CH2)6 bridging ligands. The bonding and formation of the complexes have been discussed through the use of DFT calculations combined with QTAIM analysis. The recrystallization of the mixture of the 1:1 reaction from d6-DMSO afforded [PtCl2{S(O)(CD3)2}{Te(CH2)6}] (4) that could also be characterized both structurally and spectroscopically.